Microstructure and mechanical properties of Fe-doped NiAl–28Cr–6Mo eutectic alloys

Room temperature and high temperature microstructural and mechanical properties of arc melted NiAl–28Cr–6Mo eutectic alloys doped with 0.1% Fe, 0.2% Fe and 0.5% Fe (mole fraction) were investigated. The homogenization heat treatment of the alloys was conducted at 1300 °C in Ar atmosphere. Microscopic analyses, hardness measurements, XRD measurements and compression tests were used to characterize the alloys. As-cast and homogenized alloys exhibit fine cellular eutectic structures with coarse intercellular eutectic structure. The increase in the content of Fe results in coarsening eutectic layers and the decrease in eutectic cells. All alloys have very high compressive stress and strain at room temperature. The addition of Fe has small negative impact on the strength and ductility of the alloys at room temperature. However, the addition of Fe increases the high temperature strength of the alloy. High temperature XRD patterns show that peaks shift to lower Bragg angles. This indicates that the lattice parameter of the alloys increases.